Me so mothy: Virgin male moths think they’re hot when they’re not

A University of Utah study found that when a virgin male moth gets a whiff of female sex attractant, he’s quicker to start shivering to warm up his flight muscles, and then takes off prematurely when he’s still too cool for powerful flight. So his headlong rush to reach the female first may cost him the race.

Too excited

The study illustrates the tradeoff between being quick to start flying after a female versus adequately warming up the flight muscles before starting the chase. Until the next study, it remains a mystery which moths actually reach the females: the too-cool, quick-takeoff males or the males who wait until they’re hot enough to take a shot. The latter may end up flying faster and more efficiently and win the race, despite a slow takeoff.

“What happens before flight has not been well studied,” says José Crespo, a University of Utah doctoral student in biology and first author of the new study, published online June 7 in the Journal of Experimental Biology. “To me, the story is you have a behavior – pre-flight warmup – that is switched on by smell.”

Senior author Neil Vickers, professor and chairman of biology at the University of Utah, says: “In many insects, moths in particular, all of their adult lives are affected by odor – all the activities they engage in that you and I see at night at the porch light are things typically affected by odor.”

Moths forage for nectars using flower odors. Males follow female sex attractants or pheromones to find the females. Then they have what Vickers calls “an odor dialogue” and mate. The females use odor to lay their eggs on the right plants.

“Finding out how odors switch on behavior is critical to the whole picture,” Vickers says. “Furthermore, because insects have this amazing ability to fly, which not many animals have, finding out how flight is turned on by odor is an issue relevant to many insects. … There is a whole constellation of behaviors driven by odor, and this is true of all manner of insects” and even other animals and people.

Vickers and Crespo conducted the study with University of Utah biology Professor Franz Goller. The research was funded by the National Science Foundation and National Institutes of Health.